High fiber diets have been promoted over the past several years because of the potential health benefits they offer. High fiber diets are reported to reduce the risk of colon and rectal cancers and to reduce blood serum cholesterol levels. Because dietary fiber is not well digested by humans, dietary fiber ingredients are non-caloric and contribute to a reduction in total food calories to the extent that they are used as a replacement for caloric ingredients such as carbohydrates, proteins, and fats.
The total dietary fiber (TDF) of a food or a food ingredient comprises two components: soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). It is reported that the soluble dietary fiber component is the critical component in reducing serum cholesterol. It is reported that insoluble dietary fiber health benefits achieved by consuming the fiber.
A number of dietary fibers are presently marketed as ingredients for use in formulating "healthy" food products. These fiber-containing, nutritionally-fortified, food ingredients are characterized by different fiber contents, with the highest percentage of SDF (70%) reported for Psyllium and the highest TDF (99%) reported for alpha-cellulose. The dietary fiber contents of other fiber sources are: beet fiber (75% TDF; 24% SDF); corn bran (90% TDF; 2% SDF); oat bran (20-25% TDF; 12% SDF); refined oat bran (97% TDF; 1% SDF); rice bran (27-35% TDF; 2-6% SDF); wheat bran (40% TDF; 0% SDF); pea fiber (45% TDF; 5% SDF); potato fiber (75% TDF; 15-20% SDF); Psyllium husk (87% TDF; 70% SDF); and soy fiber (75% TDF; 15% SDF).
It has been discovered that tapioca fiber, which is a by-product of the tapioca starch milling process, may be refined by the removal of residual starch to yield a refined fiber containing approximately 70% TDF and 12% SDF. The crude tapioca fiber or pulp which is the direct by-product of starch milling contains approximately 67% starch, 30% TDF and 5% SDF, on a dry-weight basis. The tapioca root in various forms (e.g., cassava or manioc; poi (Hawaii); and farina (South America and the West Indies) has been used as a source of starch in the human diet.
It has been discovered that by destarching the unrefined tapioca fiber by-product, a bland, functionally compatible dietary fiber high in TDF and SDF may be obtained. Most fiber refining processes yield high TDF and IDF levels but reduce SDF levels. Thus, it is unexpected that a product containing high amounts of both fibers may be achieved by refining a raw fiber source.
As a further advantage, it has been discovered that the unrefined tapioca fiber (as well as the refined fiber) may be used in certain human foods (e.g., cereals) wherein its unique starch and fiber components provide functional benefits to the foods.
Many foods in the bread and cereal product group are nutritionally fortified by the addition of various fibers. Serious functional problems are frequently encountered in formulating foods containing high fiber ingredients. These problems include off-flavors and colors contributed by the fiber ingredient, together with textural problems such as lack of volume or expansion in baked goods or cereals, non-uniform texture, unpredictable water holding and/or absorption characteristics, interference with the production of extruded and expanded cereals or snacks, and other related problems.
One solution to these problems has been to refine the fiber so as to eliminate the color, flavor and non-uniform texture problems. However, the refinement process usually eliminates the SDF component of the fiber.
Other means that have been suggested for formulating foods with high fiber content include preparing a fiber ingredient to contain a specific particle size to provide a food having a density within a specified range. For example, U.S. Pat. No. 4,759,942, issued Jul. 26. 1988, to Von Fulger, discloses a process for producing a high fiber breakfast cereal, wherein the fiber is used at 3-9% of the cereal and the fiber is a bran (obtained from the outer layer of grains) material having an average particle size from 5-100 microns which produces an extruded cereal having a specific density of from 0.15 to 0.40 g/cc.
It is now been found that by employing an enzymatic process to refine tapioca fiber, the SDF content of the fiber is maintained and the components of the unrefined tapioca fiber which add caloric value or detract from its use in
food formulation are effectively removed. The enzymatic destarching process may be combined with a bleaching process which also preserves the SDF content of the fiber while improving its functional characteristics, and it may be combined with particle size control to improve texture and color. Thus, a food ingredient is provided which may be used to nutritionally fortify a variety of food products by providing high TDF and SDF contents.
It has also been found that in contrast to bran derived from grains. unrefined tapioca pulp fiber may be used to fortify cereals without having an unacceptable impact on cereal functionality or quality.